Irradiation effects in the Ni-17Mo-7Cr alloy bombarded with MeV Au ions

TL;DR

This study investigates irradiation effects on Ni-17Mo-7Cr alloy using 3MeV Au ions, revealing microstrain increase, radiation-induced hardening and softening, low swelling rate, and carbon segregation, relevant for nuclear reactor applications.

Contribution

It provides systematic insights into irradiation damage mechanisms in Ni-17Mo-7Cr alloy for molten salt reactor use, including microstructural and mechanical changes.

Findings

Microstrain increased from 0.14% to 0.22% with dpa 1-30.

Radiation-induced hardening followed by softening at 30 dpa.

Swelling rate around 1.3% at 30 dpa, low per dpa.

Abstract

Irradiation effects in Ni-17Mo-7Cr alloy, which is an newly developed structural material for molten salt reactor (MSR), have been systematically investigated by using 3MeV Au ions at different fluences, corresponding to dpa number (displacement per atom) of 1~ 30. GIXRD measurement indicates that the microstrain of the irradiated samples increased from 0.14% to 0.22% as dpa increased from 1 to 30. In the meanwhile, nanoindentation results reveal the Ni-17Mo-7Cr alloy underwent radiation-induced hardening first and then softening at dpa of 30. The swelling rate of Ni-17Mo-7Cr alloy was found around 1.3% at 30 dpa, which means only 0.04% per dpa. Besides, Raman spectra shows that carbon segregation appeared after Au ions irradiation. Our results are very helpful for understanding irradiation damages in Nickel-base alloys, especially for those in purpose of being used in future MSR nuclear energy system.